Start at the root of a supporting scheme
01A URI is a resource identifier. A well-known URI starts its path with /.well-known/ and uses a scheme explicitly defined to support it.
With the hypothetical name and application rules already known, the client can address /.well-known/picnic-info. Existence and response semantics are not guaranteed by the prefix.
Source for this drawing: RFC 8615 · Read RFC section 3 ↗
New to this? Start hereA quick picture + helpful background
A message needs an address.
Think of a packet as a small addressed envelope. Devices pass it onward; transport protocols decide what delivery promises an application gets.
Helpful first, if these ideas are unfamiliar
These pictures are analogies to help you learn. The linked RFC explains the actual rules.
Terms in this drawing
- URI
- Uniform Resource Identifier: a name or address identifying a resource.
- Scheme
- The leading name, such as https, selecting URI interpretation and protocol rules.
- Path root
- The beginning of the path, immediately after the authority in these HTTPS examples.
- Origin
- For these HTTPS examples, the scheme, hostname and effective port together. A different path alone does not change the origin.
- Authority
- The host and optional port portion of these HTTPS URIs.
Related RFCs and changes
“Updates” changes part of an earlier RFC. “Obsoletes” replaces it. This list shows selected related documents.
The prefix belongs at the path root; a familiar-looking substring elsewhere does not qualify.
- The path component must begin with the literal characters /.well-known/, and the scheme must explicitly support well-known URIs. This is a definition, not a rule that arbitrary URLs containing the text acquire special meaning.
- RFC 8615 updates http and https support. ws and wss are supported through RFC 8307; other schemes need their own explicit supporting specification. The URI Schemes registry tracks this support. Do not apply this prefix automatically to every scheme.
- Well-known locations reduce collisions with applications’ own paths. They are not per-directory discovery endpoints: /foo/.well-known/example is not a well-known URI under this definition.
- Existing mechanisms such as /robots.txt are unaffected until they choose this mechanism. There is no instruction to relocate every existing discovery resource.
All picnic names and responses in this guide are fictional teaching examples, not real IANA registrations. Assume an application specification and hypothetical registration for picnic-info using https. https://api.example is the chosen origin. The nested path can be an ordinary resource; the red stop rejects its classification as a well-known URI, not an HTTP request to it.
Read the RFC section ↗